This project will identify and interview all farmers and family members treated for asthma over a 4 year period between the ages of 18 to 65 who obtain their health insurance through the Michigan Farm Bureau. It is a continuation of a project that has already been going on for 2 years. We estimate there will be approximately 1200 adults with asthma among the members during the 4 year period. All eligible subjects will be interviewed with a standardized questionnaire. Individuals who do not have documented pulmonary function testing showing hyperractive airways will be offered such testing. Using questionnaire data, we will classify subjects as having or not having work-related asthma and their type of work-related asthma. We will use the current National Institute for Occupational Safety and Health (NIOSH) Sentinel Event Notification System for Occupational Risks (SENSOR) criteria for work-related asthma to perform this classification. All subjects who meet the NIOSH SENSOR criteria for work-related asthma will be offered electronic peak flow and Forced Expiratory Volume in one second testing over a two week period, to determine if there are changes on pulmonary function testing in relation to their farm work. Prevalance rates with 95% confidence limits will be calculated for farm-related asthma. Additionally, we will compare prevalence rates using individuals who meet the NIOSH SENSOR criteria, without objective documentation of asthma and pulmonary function changes associated with farm work, versus those individuals who meet the criteria because they have objective documentation of asthma and pulmonary function changes associated with farm work. The staff performing this project is experienced in the diagnosis, management and epidemiology of asthma and work-related asthma. Dr. Rosenman who will direct the project has 15 years of experience with the Michigan SENSOR asthma surveillance system.